Blow-off nozzles are utilized in many different industries for directing compressed air onto pieces of equipment or work areas for the purpose of cleaning, blowing out, cooling, or otherwise acting upon equipment, cavities, or work surfaces. Recently, types of blow-off nozzles have been developed which comprise multi-channel flat jet nozzles presenting a plurality of individual jets disposed in a generally side-by-side linear array. One of such nozzles is available from Spraco Inc. of Nashua, N.H. and is sold under the trade name "Whisper Blast". Such nozzles have a relatively low noise level, have good blowing power and minimum air consumption, and provide good blowing force performance over a considerable distance as a result of the delivery of laminar air flow. However, such nozzles cannot be used for general blow-off applications in which a workman handles the nozzle and moves to whatever areas he sees fit, since they do not meet the regulations promulgated under the Occupational Safety and Health Act (OSHA).
OSHA requires that compressed air cannot be used for individual cleaning purposes by workmen except when reduced to less than 30 p.s.i. The reason for this is that if the nozzle at conventional compressed air source pressures of 100+ p.s.i. is placed against the body of a human, the high pressure air can penetrate the victim's skin, and is admitted into the blood vessels, which may result in serious injury. The placing of the nozzle against a surface (such as an object or part of a human's body) is referred to as "deadending", and is to be avoided. Thus, nozzles for general purpose cleaning or the like can be utilized pursuant to OSHA regulations only if at the point of delivery of air from the nozzle the pressure is less than 30 p.s.i.
Of course it is desirable to be able to utilize safety devices with nozzles in order to ensure that they cannot be "deadended". However, unless the safety device is carefully constructed and designed, it can result in a significant--and undesirable--increase in noise level. Minimization of the noise level of the nozzle is highly desirable, and a safety device must be able to perform its safety function without occasioning a significant increase in noise level.
According to the present invention, a blow-off nozzle assembly is provided wherein deadending of the nozzle is prevented, but the noise level of the nozzle is not significantly increased. The invention is particularly applicable to a multi-channel, substantially flat jet nozzle as heretofore described, and makes such a nozzle utilizable for general purpose cleaning applications since it meets OSHA requirements. However, the assembly according to the invention also has applicability to other types of nozzles.
According to one aspect of the present invention, a blow-off nozzle assembly is provided which comprises a multi-channel substantially flat jet nozzle as heretofore described and--according to the invention--means for preventing deadending of the nozzle while not significantly increasing the noise level of the nozzle. Such means comprises a generally oblong shaped guard defining a generally oblong shaped opening which is significantly larger than the dimensions of the linear array of jets. Also, means are provided for mounting the guard so that it is spaced from the nozzle in the direction of air flow through the nozzle, and so that the linear array is substantially centered within a geometric projection of the opening. The guard is preferably formed by a continuous circular cross-section rod of high impact plastic (such as nylon), and mounting means include a pair of circular cross-section posts which are integral with the rod and extend from one side thereof. The posts straddle the linear array of jets during use, and preferably are received within channels defined in an outer casing for the nozzle.
It is also desirable to be able to protect the nozzle should it be dropped, since the nozzles are typically subjected to rough handling in general purpose cleaning applications. The nozzle protecting function is nicely integrated with the safety function according to the invention by providing an outer shell of high impact resistant plastic (e.g. nylon) substantially surrounding the nozzle, with the jets extending outwardly from a front end of the casing, and a connection to a source of air under pressure being provided at the rear end of the casing, opposite the front end. Impact absorbing material, such as a plastic foam or rubber, is disposed between the shell and the nozzle, and the shell defines channels for receipt of the guard support posts.
It is the primary object of the present invention to provide a safe and versatile blow-off nozzle assembly without increasing the noise level of the nozzle. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.